The present invention, in some embodiments thereof, relates to an apparatus and a method for capturing an image and, more particularly, but not exclusively, to an apparatus and a method for capturing a digital image that depicts a scene with moving objects.
In recent years, the demand for high performance compact digital imaging devices has increased. Such imaging devices convert an image of an intercepted scene into electronic signals by using an image sensor, such as a charge-coupled device (CCD) based sensor or a complementary metal-oxide semiconductor (CMOS) based sensor. In particular, the demand for high performance compact digital imaging devices, which are designed to be mounted in a compact device, such as a mobile phone, and have image sensors that have large numbers of pixels, for example more than two million pixels, is increasing. Such a demand is an outcome of the prevalence of mobile devices that incorporate digital cameras, such as laptops, webcams, mobile phones, personal digital assistants (PDAs) and the like.
Such imaging devices are usually designed to capture both still images and video sequences. Capturing a video sequence requires more computational complexity than capturing a still image and the memory which is needed to store large amount of input video frames is relatively high. I common technique to avoid the high demand of computational complexity and memory, is to capture and/or store the input video frames in low resolution.
Because of capturing a still image and capturing a video sequence are two different modes of operation, a user desiring to capture both video images and high resolution still images of a scene must switch modes, likely resulting in the shot being missed.
A number of methods have been developed to overcome this problem, for example U.S. Pat. No. 7,148,919, granted on Dec. 12, 2006 discloses an imaging system operable to substantially simultaneously capture still image data and video data. The imaging system includes an optical system capturing incident light representative of an image and an integrated circuit. The integrated circuit includes at least one sensor receiving the incident light and substantially simultaneously generating the still image data and the video data within an exposure window. The imaging system also includes a controller transmitting signals to the integrated circuit for controlling the generation of the still image data and the video data.
Another example is U.S Patent Application No. 2004/0246344, published on Dec. 9, 2004 that discloses a method is disclosed for capturing images, including reading image data in an image sensor from a photodetector array in the image sensor, and processing the image data in the image sensor. The method alternates between processing the image data to generate video frames and to generate portions of still images. A plurality of video frames are processed in the time it takes to process a complete still image. The video frames have a lower resolution than the still images.